PLAYOFF PUSHHow to Read Futures Odds: American Odds, Implied Probability and the Vig
Every team page on Playoff Push shows two numbers about the same team: our simulated playoff odds, and the sportsbook's price to win the championship. They look like they should agree and they usually do not, because they are measuring different things in different units. This guide explains how to read the sportsbook's number, how to turn it into a percentage, and how to compare the two honestly.
What a futures bet is
A futures bet settles at the end of a season: a team to win the World Series, the Super Bowl, the Stanley Cup, the NBA title, the Premier League or the Champions League. Books also offer futures on division winners and on making the playoffs, though those markets are thinner and not every book posts them.
Futures prices move all season long. A team that starts at +1200 and gets hot may be +500 by August; a team that suffers an injury drifts out to +4000. The price you see is the book's current view combined with where its customers' money has gone.
American odds in thirty seconds
North American books quote American odds, also called moneyline odds:
- A positive number is the profit on a $100 stake. +700 means a $100 bet returns $700 in profit plus your $100 back.
- A negative number is the stake needed to win $100. -150 means you must risk $150 to win $100.
Favourites carry negative numbers, underdogs positive ones. In a futures market with twelve or more teams almost everyone is a positive-odds underdog.
Converting odds to implied probability
Implied probability is the break-even chance a price represents. If a team wins exactly that often, you neither make nor lose money over time.
Positive odds: implied probability = 100 / (odds + 100)
Negative odds: implied probability = odds / (odds + 100), using the number without the minus sign
| Odds | Calculation | Implied probability |
|---|---|---|
| +100 | 100 / 200 | 50% |
| +300 | 100 / 400 | 25% |
| +700 | 100 / 800 | 12.5% |
| +2500 | 100 / 2600 | 3.8% |
| +7000 | 100 / 7100 | 1.4% |
| -150 | 150 / 250 | 60% |
| -400 | 400 / 500 | 80% |
Our futures card shows this conversion for the best available price so you do not have to compute it.
Why the percentages do not add to 100
Add up the implied probabilities of every team in a championship market and you will get something like 118% or 125%. The excess is the book's margin, called the vig, the juice, or in European terminology the overround. It is how the sportsbook makes money regardless of who wins.
On a single game with two sides the vig is typically 4 to 5%. On a futures market with thirty teams it is usually far larger, because the book pads every long shot. A team at +7000 might carry a "true" probability closer to 1% than the 1.4% the price implies. Futures are, for this reason, among the worst-value bets a casual bettor can make. The margin is high and your money is tied up for months.
Removing the vig
To compare a book's price to a real probability you have to strip the margin. The simplest method divides each team's implied probability by the total:
Fair probability = implied probability / sum of all implied probabilities
If the market totals 120% and a team's raw implied probability is 12%, its vig-free probability is 12 / 120 = 10%. This proportional method is not perfect, because books do not spread their margin evenly, and long shots tend to be padded more, but it is close enough for comparison.
Comparing the book to a model
Now the two numbers on a Playoff Push team page can be put side by side, with two cautions.
First, they measure different events. Our odds are the probability of making the playoffs. The book's futures price is for winning the championship, a much harder thing. A team with a 60% chance of making a twelve-team playoff might have a 6 or 7% chance of winning it all, so a title price around +1400 is consistent with those playoff odds, not in conflict with them.
Second, our model is deliberately simple. It knows standings, schedule and home advantage; it does not know injuries or pitching matchups. The book knows all of that plus the market. Where the two disagree sharply, the book is more often right about the present, and the model is more often right about the arithmetic of the remaining schedule. The interesting cases are the ones where the standings math says a team is nearly certain to qualify and the book's title price seems to ignore it, or the reverse.
Shopping for price
Books differ. The same team can be +650 at one book and +800 at another on the same afternoon. The futures card lists every book's price with the best one highlighted. Over a season, always taking the best available number is worth several percentage points of margin, more than any handicapping insight most bettors will ever have.
Some of the links on the card are affiliate links, marked "ad." Following one may earn us a commission at no cost to you; it does not change which book is shown as the best price, which is purely the number.
Rules of thumb
- Convert to a percentage before you judge a price. +700 sounds like a lot; 12.5% is easier to reason about.
- Add up the market. The further above 100% it sits, the more you are paying for the privilege.
- Compare like with like: playoff odds against playoff odds, title odds against title odds.
- Shop the price. The difference between books is free money you either take or leave.
- Bet what you can lose, and never on a race you are emotionally invested in without noticing that you are. Our guide to betting responsibly on playoff races has more on that.
Lines on Playoff Push come from The Odds API and are refreshed a few times an hour. They are shown for information only; check the sportsbook for the current price before betting.
Frequently asked questions
- How do you convert American odds to a percentage?
- For a positive number like +700, divide 100 by the odds plus 100: 100 / 800 = 12.5%. For a negative number like -150, divide the odds by the odds plus 100, ignoring the sign: 150 / 250 = 60%.
- Why do implied probabilities add up to more than 100%?
- The extra is the sportsbook's margin, called the vig or the overround. On a futures market with many teams it can add up to 20% or more, which is why futures are a poor-value bet unless you have a real edge.
- What is a futures bet?
- A bet on something decided at the end of the season rather than in one game: a championship winner, a division winner, or a team to make the playoffs.
- Are playoff odds from a model the same as betting odds?
- No. Model odds estimate a probability from standings and schedule. Betting odds are prices that include the book's margin and shift with where money is being wagered.